Mean confidence interval
Construct a z interval with a known population standard deviation.
How this works
Mean ± zσ/√n. Enter a critical value for your confidence level.
Example
Using the example inputs, confidence interval is 48.04 to 51.96.
- Sample mean
- 50
- Known population standard deviation
- 10
- Sample size
- 100
- Critical z value (1.96 ≈ 95%)
- 1.96
- Confidence interval
- 48.04 to 51.96
Scope and assumptions
Requires independent observations and a normal sampling distribution with known population σ; not a small-sample t interval.
NIST statistical methods handbook